重复加热对加剂改性原油蜡晶形态与结构的影响

Effect of reheating on the morphology and structure of wax crystals in PPD-beneficiated crude oil

研究重复加热对加剂改性CQ原油宏观流动性与微观蜡晶形态的影响,有助于探究重复加热影响降凝剂改性效果的内在原因。对降凝剂改性CQ原油进行重复加热实验,研究发现重复加热对改性CQ原油蜡晶形态与结构的影响规律与对流动性的影响存在对应关系:将加剂CQ原油预热至60℃后再动态降温至20℃,然后重复加热至不同温度,当重复加热温度小于35℃时,随重复加热温度的升高,蜡晶尺寸减小,分形维数变小,改性油的宏观流动性变差;当重复加热温度为35℃时,蜡晶尺寸与分形维数达到最小值,降凝剂改性效果完全丧失;当重复加热温度大于35℃时,随重复加热温度的升高,蜡晶尺寸与分形维数逐渐增大,改性油的宏观流动性逐渐变好;重复加热恶化温度区间与原油的析蜡点到溶蜡点温度区间对应。研究成果为分析重复加热对加剂原油流动性的影响提供理论支撑。(图5,表5,参24)

The study on the influences of reheating on the macroscopic flowability and microscopic wax crystal morphology of CQ crude oil beneficiated with pour point depressant （PPD） is beneficial to explore how reheating inherently influences the modification effect of PPDs. In this paper, reheating experiments were conducted on PPD-beneficiated CQ crude oil. It is shown that the influential law of reheating on the morphology and structure of wax crystals corresponds to its effect on the flowability of PPD-beneficiated CQ crude oil. After PPD-beneficiated CQ crude oil is preheated to 60 ~C and then cooled dynamically to 20 ~C, it is reheated to different temperatures. When the reheating temperature is below 35 ~C, the size of wax crystals decreases, the fractal dimension becomes smaller and the macroscopic flowability of modified oil becomes worse with the increase of reheating temperature. When the reheating temperature is 35 ~C, the wax crystal size and fractal dimension reach the minimum value, and the modification effect of PPD is lost completely. When the reheating temperature is over 35 ~C, the size of wax crystals and the fractal dimension increase and the macroscopic flowability of modified oil gets better gradually with the increase of reheating temperature. The temperature range in which reheating deteriorates the modification effect of PPD seriously is corresponding to interval from wax appearance temperature （WAT） to wax dissolution temperature （WDT） of crude oil. The research results provide the theoretical support for the study on the influences of reheating on the flowability of the modified oil. （5 Figures, 5 Tables, 24 References）